The Rim of the Valley Corridor Special Resource Study was called for by Congress in 2008. That measure directed the Park Service to study more than 650,000 acres of the mountains encircling the San Fernando, La Crescenta, Santa Clarita, Simi, and Conejo Valleys of Los Angeles and Ventura counties for inclusion in the National Park System. The study area also includes the majority of Santa Monica Mountains National Recreation Area and portions of the Angeles National Forest that serve as the headwaters of the Los Angeles River. Approximately half of the acreage of the study area is publicly owned.

Santa Monica Mountains National Recreation Area was designated a unit of the National Park System in 1978. Within its borders the NRA includes 150,000 acres of private, local, state and federal lands under a unique partnership umbrella in which the federal government owns approximately 15 percent of the land.

Expanding the NRA to include the acreage in the Rim of the Valley Corridor would benefit hikers, bikers, rare vegetation, and wildlife, according to NPCA officials.

“The greater Los Angeles metropolitan area is our nation's second most populated—and it continues to grow. As it does, the need for additional open space for both humans and wildlife becomes critical,” said Seth Shteir, the park advocacy group's California desert field representative.

With the current comment period scheduled to end Oct. 29, NPCA officials are suggesting that the public call on the Park Service to expand the Santa Monica Mountains Recreation Area to include the Rim of the Valley Corridor Special Resources Study area; enhance recreational opportunities by completing the Rim of the Valley Trail work that will link the San Fernando, La Crescenta, Santa Clarita, Simi, and Conejo Valleys; evaluate wildlife corridors between the Santa Susana Mountains and Los Padres National Forest, and; study the feasibility of a “Transit to Trails” alternative transportation system that can bring urban residents without cars to key trailheads and ensure access to open space for all Los Angeles residents.

Perhaps it's coincidence, but at the same time public comment was being solicited on this proposal, Santa Monica Mountains NRA and U.S. Geological Survey officials released a report describing how the NRA was becoming an ecological island surrounded by urban areas that were impacting the ability of lizards and birds to remain genetically rich.

In approaching their task, the researchers compared "the DNA of animals collected throughout the now-isolated scrubland patches and parks surrounding Thousand Oaks and State Route 23 — an area that was a single, mostly contiguous wilderness only 50 years ago."

"They found that animals in these 'habitat islands' have unique genetic profiles, so that individuals even in closely neighboring patches are unlikely to be related," a park release explained. "Additionally, animals within the smaller or more isolated habitat patches are closely related to one another. The data showed that the populations of lizards and wrentits have become disconnected and isolated as their natural habitats became divided and fragmented by roadways and housing.

"As the animals are unable to cross these urban barriers, they begin to inbreed and lose their genetic diversity. Decreased genetic diversity may increase a species’ chance of extinction."

You can find more information on the Rim of the Valley study at this site, and submit comments at this site.